Erectile dysfunction (ED) is the inability to get or keep an erection that is firm enough, or lasts long enough, to have successful sexual intercourse. It can have serious effects on a person's sexual relationship and their self-esteem. Erectile dysfunction is caused by several factors that contribute to erection and ejaculation. Physical and mental stimulants, hormones, neural transmissions and feedback, muscle contractions and relaxations, and cardiovascular blood flow all work together to create and maintain an erection leading to ejaculation. When any of these processes are disrupted, it can cause erectile dysfunction. The causes of ED are generally divided into two major categories: those that are psychological in nature and those that are physical (or organic) in nature.
When treating ED, there are many options to choose from, depending on the cause and nature of the problem. The treatments include: psychological, oral medications, vacuum pumps, transurethral therapy, injection therapy and surgical treatments. To treat a psychological cause, a doctor may recommend treatment from a qualified psychologist, psychiatrist, sex therapist or marriage counselor. Counseling can often resolve any psychological problems causing ED. Non-invasive treatments for ED include oral medications such as Viagra®, Cialis® and Levitra®. These medications improve blood flow to the penis by working directly on the blood vessels. They allow the arteries to expand, which could produce an erection. Pills are generally taken about an hour to several hours before planned sexual activity and must be combined with sexual stimulation to provide an erection. Vacuum pump therapy may be prescribed as a non-invasive treatment. When an erection is desired, the vacuum constriction device is placed over the penis. By withdrawing air, a vacuum is created, mechanically enhancing the flow of blood into the penis. A rubber ring placed around the base of the erect penis traps the blood inside the penis and maintains the erection. Transurethral therapy includes using an applicator, the patient inserts a small pellet of medication into the urethra opening at the end of the penis. The medication is absorbed into surrounding erectile tissue, causing blood vessels to relax so the penis fills with blood and becomes erect. Injection therapy uses a needle to inject medication directly into the base of the penis. The relaxation of muscle tissue allows blood to flow into the penis creating an erection. Finally, a penile implant, or a penile prosthesis, is concealed entirely within the body and requires some degree of manipulation before and after intercourse to make the penis erect or flaccid. There are different types of implants based on the manner of operation, naturalness of the erection and the number of components implanted.
A three-piece inflatable penile prosthesis provides a more natural appearing erection than the two-piece or malleable implants. A three-piece penile prosthesis typically consists of a pair of cylinders implanted in the corpus cavernosa, a single pump bulb implanted in the scrotum, and a reservoir implanted in the abdomen. This three-piece prosthesis acts and feels more like a natural erection compared to one-piece implants or two-piece implants. The three-piece prosthesis also expands the girth of the penis. Moreover, the three-piece feels softer and more flaccid when deflated compared to one-piece implants or two-piece implants. However, the three-piece prosthesis does have some challenges when in use such as the requirement of some manual dexterity, possibility of leakage, malfunction causing unintentional erections and implantation of a reservoir in the abdomen.
A two-piece inflatable prosthesis typically consists of a pair of cylinders implanted in the corpus cavernosum and a single pump bulb implanted in the scrotum. Patients simply squeeze the pump to inflate and bend the penis to deflate the prosthesis. This closed, fluid-filled system allows for good rigidity and partial flaccidity. Moreover, the two-piece penile prosthesis does not require an abdominal incision. However, the two-piece prosthesis does have some challenges when in use such as reduced flaccidity
Both the three-piece and the two-piece penile inflatable prostheses rely on the transfer of a volume of fluid to and from the inflatable cylinders to transition the cylinders between inflated and deflated states. It is desirable to reduce this volume of fluid to reduce the amount of pumping required to be performed by the patient, and to reduce the size of the prosthesis.